Integrated device technology depends heavily on the use of metallization layers and the patterning of such layers on semiconducting and insulating materials. Typically, such materials are doped or undoped silicon, gallium arsenide, other binary, ternary, or quaternary III-V, or II-VI semiconductor materials, or insulating materials such as, e.g., silica, alumina, and polymeric layers.
The suitability of a material as a metallization material depends on a number of materials properties such as, e.g., electrical conductivity, electrical contact resistance, stability of such electrical properties over time, physical integrity and adhesion, and the availability of a suitable etchant in photolithographic processing. Among such metallization materials are gold, aluminum, alloys of aluminum and copper, and composite or multi-layer systems; see, e.g., documents as discussed below for specific materials and their processing.
U.S. Pat. No. 3,657,029, issued Apr. 18, 1972 to C. R. Fuller is concerned with a multi-layer metallization method in which a layer of platinum, palladium, rhodium, ruthenium, osmium, or iridium is etched using chromium or titanium as a mask material.
U.S. Pat. No. 3,881,884, issued May 6, 1975 to H. C. Cook et al. discloses the manufacture of a composite conductive layer comprising an exposed layer of gold, platinum, palladium, iridium, rhodium, ruthenium, or osmium.
U.S. Pat. No. 4,017,890, issued Apr. 12, 1977 to J. K Howard et al. discloses the use of an intermetallic compound of aluminum and a transition metal such as palladium, platinum, chromium, hafnium, zirconium, antimony, titanium, tungsten, vanadium, tantalum, cobalt, or nickel as a semiconductor metallization.
U.S. Pat. No. 4,039,698, issued Aug. 2, 1977 to D. B. Fraser et al. discloses platinum metallizations and is particularly concerned with a method for making such metallizations.
The paper by J. A. Armstrong et al., "Transition Metal Oxide Conductors in Integrated Circuits", IBM Technical Disclosure Bulletin, Volume 20, No. 11A, April 1978 discloses the suitability of certain metal oxides such as molybdenum, ruthenium, rhodium, osmium, iridium, and platinum oxides as metallization materials, such materials having resistivities which are only about 5 to 25 times those of copper, molybdenum, gold, and an aluminum-copper-silicon alloy.